Rate of cannabis use disorder during pregnancy increased over 20% after cannabis legalization in Canada

In October 2018, Canada enacted the Cannabis Act in Canada (CAC), which legalised the non-medical use of cannabis.  A new study has found that the rate of cannabis-related disorders diagnosed among pregnant women in the Canadian province of Québec increased by more than 20% after the enactment of the CAC, while rates for all other drug- and alcohol-related disorders remained stable.  The study is published today in the scientific journal Addiction.

This study measured changes to the monthly rates of diagnosed cannabis-related disorders (CRDs) in the pregnant population in Québec.  Since 2010 the monthly average number of CRDs has increased consistently, and before October 2018, the average number of CRD diagnoses per month was 14.5 per 100,000 pregnant women.  After October 2018, the average number of CRD diagnoses per month jumped to 23.5 per 100,000 pregnant women and has remained at that higher level.  There were no significant changes for any other drug- and alcohol-related disorders in the same period. 

The study looked at rates of CRD diagnoses in pregnant women aged 15 to 49 years in the Canadian province of Québec between January 2010 and July 2021.  Data were sourced from the Québec Integrated Chronic Disease Surveillance System (QICDSS). Given that approximately 98% of the Québec population is eligible and admissible to public health insurance, the QICDSS encompasses data for nearly the entire population of the province.

Lead author Professor José Ignacio Nazif-Munoz, of the Université de Sherbrooke, says: “Cannabis use during pregnancy has been associated with elevated risk of preterm birth, neonatal intensive care unit admissions, low birth weight, and other negative outcomes, so the increase in CRD diagnoses after the Cannabis Act should trigger a robust public health response.  Our study highlights the importance of universal screening for CRDs.  Additionally, pregnant women with a history of cannabis disorder may benefit from repeated screening and ad-hoc counselling during pregnancy.”

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For editors:

This Open Access paper is available online (https://onlinelibrary.wiley.com/doi/10.1111/add.16564) or you may request a copy from Jean O’Reilly, Editorial Manager, Addiction, jean@addictionjournal.org.

To speak with lead author Prof. José Ignacio Nazif-Munoz, please contact him at the Université de Sherbrooke by telephone (+1 438 502 5210) or email (nazj1501@usherbrooke.ca).

Full citation for article: Nazif-Munoz JI, Martínez P, Huỳnh C, Massamba V, Zefania I, Rochette L, and Vasiliadis H-M. Changes in prenatal cannabis-related diagnosed disorders after the Cannabis Act and the COVID-19 pandemic in Quebec, Canada. Addiction. 2024. https://doi.org/10.1111/add.16564

Primary funding: This study was funded by Fonds de recherche Societé et Cultures (project number 322560). Pablo Martínez acknowledges the Fons de Recherche du Québec sur la Nature et les Technologies (FRQNT-PBEEE) postdoctoral fellowship. We also received some support from Institut universitaire sur les dépendances. The sponsors had no further role in the study design, data analysis and interpretation, the dating of the manuscript or the decision to submit this article for publication.

Declaration of interests: The authors declared no competing interests.

Addiction (www.addictionjournal.org) is a monthly international scientific journal publishing peer-reviewed research reports on alcohol, substances, tobacco, gambling, editorials, and other debate pieces. Owned by the Society for the Study of Addiction, it has been in continuous publication since 1884.